Railway signaling



July 19, 1938. G. R. PFLASTRER RAILWAY SIGNALING Filed March 12, 1936 8 Sheets-Sheet l July 19, 1938. G. R. PFLAsTr-:RER

RAILWAY SIGNALING Filed March l2, 1936 8 Sheets-Sheet 2 2 6 uw 3 2 l 2 July 19, 1938.

G. R. PFLASTERER RAILWAY SIGNALING 8 Sheets-Sheet 3 Filed March l2, 1936 Y fi.

my www ww INVENTOR George J @POP ATTORNEY July 19, 1938.

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RAILWAY S IGNALING Filed March 12, 19:56 8 sheets-sheet 6 am @mw LJI.

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HIS ATTORN EY July 19, 1938. G.-R. PFLASTERER RAILWAY SIGNALING Filed March 12, 19:56

8 Sheets-'Sheetr 7 QJ E A A v J NUL RW Y Nvlwhw v i mp m vl NMI f Y .L 4 n QSNT S www wp RNS Qm mi m D. E E Q. MEW@ .IIQ Y .NQS W B H u ..WN M @NTAMWM M C %Q- M @wm G m. HT a SWL... .vwo L REM IFI l d im q l d l s, E N sm wv w WN Q ENS July 19, 1938. GQR. PFLASTERER RAILWAY S IGNAL ING Filed March l2, 1936 BSheets-Sheet 8 NSI MS2 SNE lLl ferez George Z HIS ATTORNEY Patented July 19, 1938 UNITED STATES farisei orme-.E

RAILWAY SIGNALING Application March 12, 1936, Serial No. 68,497

15 Claims.

My invention relates to railway signaling, and particularly to signaling involving wayside signals located along a trackway for governing the passage of trains.

A feature of my invention is the provision of novel and improved apparatus for establishing a distinctive control for each of three sections in therear of an occupied section. Each distinctive control iseiective to cause a corresponding aspect of the wayside signals whereby there is produced a three block, four indication system of signaling.

The apparatus provided by this invention is an improvement on the systems shown in the application of Howard A.V Thompson, Serial No. 692,155, filed October 4, 1933, for Railway traic controlling apparatus, and in the application of Henry S. Young, Serial No. 66,002, led February 27, 1936, for Railway signaling.

I will describe several forms of apparatus each embodying my invention, and will then point out the novel features thereof in claims.

In the accompanying drawings, Figs. 1A and 1B are diagrammatic views which, when placed end to end in the order named, illustrate one form of apparatus embodying my invention. Figs. 2A and 2B are diagrammatic views which, when place-d end to end in the order named, illustrate another form of apparatus embodying my invention. Figs. 3A and 3B are diagrammatic views which, when placed end to end in the order named, illustrate still another form of apparatus embodylngmy invention. Fig. 4 is a diagrammatic view illustrating in detail a portion of the apparatus illustrated in the foregoing figures. Figs. 5A and 5B are diagrammatic views which, when placed end to end in the order named, illustrate still a diierent form of apparatus embodying my invention.

Similar reference characters refer to similar parts in each of the several Views.

rlf'teferring rst to Figs. lA and 1B, the reference characters 8 and 9 designate the rails of a stretch of railway track along which traic normally moves in the direction indicated by the arrows. These lrails are divided by insulated joints I4 into a plurality oi track sections or blocks W-X, X-Y, and Y-Z.

Each track section is divided by insulated joints I4 into at least two subsections iT, 2T, 3T, 4T, etc. Each subsection is provided with a track circuit which includes a track battery l5 connected across the rails at one end of the subsection and a track relay connected across the other end of the subsection. The track relays are designated .by the reference character TR with a prefix the same .as the numerical prefix inthe reference character for the associatedsubsection.

To Vgovern .the passage of trains through'the stretch of railway,.gJ wayside signal, designated by a suitable distinguishing reference character, is located at the entrance to each track section. Each ofy these signals comprises an upper unit U and alower unit L. These units may take any lamp Y, and a redlamp R; and each lower unit is a color light signal comprising a, green lamp G and a red lamp R.

Each section isprovided with` apolarizeddirect current signal control relay designated by the referencecharacter H vvitha.` prex the same as the reference character of the associated signal and with an Aalternating currentsignal control relay designated by the reference character J with a -prex the .same as the reference character of the associatedsignal.

Each section is provided with aline circuit includingapair Ofiline wires extending'to the signal nextin advance ancleachfof which includes a front` contact of each of the associated `track relays. f

Each relayH is connected directly to the associated-line wires and each relay J is also -connected tothe associated line wires'through a, condenser designatedby the reference ycharacter D .with a prefix the same as the reference character of the associated signal.

The condensers D Vprevent the ow'of direct current in the alternating current-relays J and the high impedance of the direct current relays I-I prevents the flow of alternating current in these relays.

Each section is provided with a suitablesource of direct current, the terminals of which aredesignated by the reference characters B and C.

Each section is also provided with a device for converting the direct current into alternating current and designated by the reference character A with a prex the same as the reference character of the associated signal. As here shown, the devices A are the well known tuned reed alternators.

Associated with each alternator A is a transformer N, the primary winding of which is connected to the associated alternator and the secondary'winding of which is at times eiective to supply alternating current to the line circuit for the section next in rear.

As will be explained more in detail hereinafter, the relays H and J control the line circuit for the section next in rear in such manner that this line circuit is supplied with direct current of one polarity or with direct current of the other polarity or with alternating current.

Each of the color light signals is controlled by the associated relays H and J in the following manner: When both relays are deenergized (see signal I3) the red lamp R of the upper unit U of that signal is lighted by a circuit which passes from terminal B through back point of contact IG of relay ISH, back point of contact I1 of relay l3J, and lamp R to terminal C; and the red lamp R of the lower unit L of that signal is lighted by a circuit which passes from terminal B through back point of contact I8 of relay I3H and lamp R to terminal C. Signal I3, therefore, displays a red light above a red light to indicate stop. When relay H is deenergized and relay J is energized (see signal I2) the yellow lamp Y of the upper unit U of that signal is lighted' by a circuit which passes from terminal B through back point oi Contact I9 of relay I2H, front point of contact 20 of relay I2J, and lamp Y to terminal C; and the red lamp R of the lower unit L of that signal is lighted by a circuit which passes from terminal B through back point of contact 2I of relay IZH and lamp R to terminal C. Signal I2, therefore, displays a yellow light above a red light to indicate prepare to stop at next signal. When relay H is energized in the reverse direction (see signal I I) the yellow lamp Y ofthe upper unit U of that signal is lighted by a circuit which passes from terminal B through front point of contact 22 of relay IIH, reverse polar contact 23-24 of relay I IH, and lamp Y to terminal C; and the green lamp G of the lower unit L of that signal is lighted by a circuit which passes from terminal B through front point of contact 25 of relay I IH, reverse polar contact 26-21 of relay IIH, and lamp G to terminal C. Signal II, therefore, displays a yellow light above a green light to indicate approach next signal at medium speed. When relay H is energized in the normal direction (see signal I0) the green lamp G of the upper unit U of that signal is lighted by a circuit which passes from terminal B through front point of contact 28 of relay I 0H, normal polar contact 23-29 of relay IDH, and lamp G to terminal C; and the red lamp R of the lower unit L of that signal is lighted by a circuit which passes from terminal B through front point of contact 3l! of relay IOH, normal polar contact 2li-3| of relay IDH, and lamp R to terminal C. Signal I I), therefore, displays a green light above a red light to indicate proceed at normal speed.

As shown in the drawings, the section immediately to the right of point Z is occupied by a train K, so that both relays ISH and I3J are deenergized. When relays I 3H and I3J are deenergized, alternator I3A is supplied with direct current energy over a circuit which passes from terminal B through back contact 32 of relay I 3H, back contact 33 of relay I3J, wire 34, and alternator I3A to terminal C, so that alternator I 3A supplies alternating current to the primary winding 35 of transformer I3N. When alternating current is supplied to primary winding 35 and both relays I3H and I3J are deenergized, alternating current relay I2J is energized by alternating current over a circuit which passes fromvone ter- Ininal of secondary winding 36 of transformer ISN through wire 31, back point of contact 38 of relay I 3J, back point of contact 39 of relay I 3H, front contact 40 of track relay GTR, front contact 4I of track relay STR, relay I 2J, condenser I2D, front contact i2 of relay ETR, front contact 43 of relay GTR, back point of contact 44 of relay I3H, back point of contact 45 of relay ISJ and wire 46 to the other terminal of primary winding 36. When relay I2J is energized and relay I2H is deenergized, relay II H is energized by direct current in the reverse directionover a circuit which passes from terminal B, at signal I2, through front point of contact 4l of relay IZJ, back point of contact 43 of relay IZH, front contact 49 of relay ITR, front contact 56 of relay STR, relay I IH, front contact 5l of relay 3TR, front contact 52 of relay @.TR, back point of contact 53 of relay I2H, and front point of contact 54 of relay IZJ to terminal C. When relay IIH is energized, relay 50H is energized by direct current in the normal direction over a circuit which passes from terminal B through front point of contact 55 of relay IIH, front contact 5E of relay ZTR, front contact 5l or" relay ITR, relay ISH, front contact 58 of relay ITR, front Contact 59 of relay ZTR, and front point of contact 68 of relay IIH to terminal C. It will be readily apparent that When relay HUH is energized the line circuit for the section next in rear of section W-X is supplier over front contacts of relay ISH, with direct current energy in the normal direction so that the signal (not shown) for such rear section is displaying its normal proceed indication.

'I'o sum up thus far, each signal is controlled by a direct current polarized signal control relay and by an alternating current signal control relay both receiving energy over a line circuit which is controlled by the track relays of the section with which the signal is associated and by the signal control relays of the signal next in advance. When both signal control relays are deenergized the associated signal indicates top and the line circuit to the rear is supplied with alternating current energy only. When the alternating current relay alone is energized the associated signal indicates prepare to stop at next signal and the line circuit to the rear is supplied only with direct current of reverse polarity. When the direct current relay is energized in the reverse direction the associated signal indicates approach next signal at medium speed and the line circuit to the rear is supplied only with direct current of normal polarity. When the direct current relay is energized in the normal direction the associated signal indicates proceed at normal speed and the line circuit to the rear is supplied orLly with direct current of normal polarity so that the signal controlled by such rear line circuit will also display the normal proceed indication.

It will be noted the alternator A at each signal is caused to operate only when the associated section is occupied by a train. Since under ordinary conditions the stretch of railway will be unoccupied the greater part of the time, the energy consumed by the alternators will be relatively small. This feature, therefore, provides a simple and economical method for providing alternating current at each signal which method is particularly desirable when the direct current energy is supplied by primary batteries Which must be renewed from time to time.

It will also be noted the polarized signal control relays H are of the retained neutral type, that is, the neutral armatures of these relays do not release during changes of polarity. This characteristic prevents momentary hashing of a red lamp of the associated signal and tumbledown of the signal control relays to the rear. For example, when the train K vacates the section to the right of location Z so that the line circuit for the section X-Y is supplied with direct current energy in the normal direction to cause signal l! to display a green light above a red light instead of a yellow light above a green light, the neutral contacts oi relay l IH will remain in their energized position, as shown in Fig. 1A, during the period of change in polarity. Since 'the back points of the neutral contacts of relay HH do not become closed, the circuit for the red lamp R of the upper unit U of signal Il cannot become closed to cause a momentary flash of that lamp, and since the front points of the neutral contacts of relay l IH do not become opened, the line circuit for the section W-X will remain closed so that the energization of relay WH will not be disturbed. Consequently, momentary hashing of the red lamps and successive tumble-down of the signal control relays to the rear are avoided.

Each of the retained neutral polarized signal control relays H functions, during pole-changing periods, in a manner similar to that described for relay MH.

Referring next to Figs. 2A and 2B, the system illustrated herein functions in many respects similar to that described for the system illustrated in Figs. 1A and 1B. The principal diierence is in the type of Wayside signal utilized. As here shown, each upper unit UA is a signal mechanism of the searchlight type which may be substantially as described and claimed in United States Letters Patent No. 1,864,224, issued June 21, 1932, to' VV'. B. Wells for Light signal; and each lower unit LA is a lamp Y capable of displaying a yellow light. For the purpose of this application it is deemed su-lcient to but brieiiy describe these searchlight signals. Upper unit UA of signal l0, for example, includes a pivotally mounted rotor 62 controlled by a permanent magnet (not shown) and by an operating winding 63. Energization of operating Winding B3 by current of one polarity causes rotor 62 to be rotated in one direction, moving the signal to the clear indication position; energization of operating winding 53 b-y current of the other polarity causes rotor S2 to be rotated in the opposite direction to move the signal to the caution indication position; while deenergization of operating Winding @El permits rotor 62 to be released by gravity to a center position, which is the stop indication position. Associated with rotor G2 is a signal lamp MBE. As pointed out in detail in the aforementioned patent, when rotor 62 is rotated to the clear position, a green colored filter G is moved in front of lamp IDE', so that a green signal light is displayed when lamp lllE is lighted. When rotor S2 is rotated to the caution indication position, a yellow colored filter Y is moved in front of lamp IDE so that a yellow signal light is displayed When lamp HlE is lighted.

v acter ER with a prefix the s ame as the reference character of the associated signal and connected in series With the line circuit for the section next in rear only when that line circuit is supplied with direct current energy.

Each lamp E is controlled by a back contact of the associated relay ER so that whenever the approach lighting relay is deenergized the associated lamp is lighted. For example, the lamp 13E is controlled over an easily traced circuit which includes back contact Sl of relay ISER. Since each of the other lamps E` is controlled in a similar manner by the associated relay ER, it Will be obvious that each lamp E' will be lighted Whenever the associated relay ER is deenergized; that is, Whenever the line circuit controlling such relay is opened or is supplied with alternating current energy. In other Words, the relays ER will become deenergized Whenever the associated section or the section next in rear becomes occupied by a train.

Each section is provided with the usual direct current polarized relay signal control relay H of the retained neutral type and with a direct current neutral signal control relay V.

Both signal control relays receive energy over the usual line circuit extending to the signal next in advance and controlled by the track relays of the associated section and by the two signal control relays of such advance signal. The polarized relay H is connected directly to the associated line circuit and the neutral relay V is connected to the associated line circuit through a rectifier, a transformer and a resistor designated bythe reference characters Q, M, and E', respectively, each with a prefix the same as the reference character of the associated signal.

The resistors F will prevent the excessive flow of direct current in the primary windings of the transformers M, and the transformers M Will prevent the flow oi any direct current in the relays V. The high impedance of the direct current relays H will prevent the flow of alternating current in these relays.

Associated with each section is the usual alternator A and transformer N both of which are controlled by the associated relays H and V in a manner similar to that described for the apparatus shown in Figs. 1A and 1B. That is, whenever a section is occupied by a train, the alternator A is connected to the source of direct current and the secondary winding 3S of the transformer N is connected to the line circuit for the section next in rear to supply that line circuit with alternating current energy.

The relays H and V control the associated signals in the following manner: When both relays H and V are deenergized (see signal I3) both operating windings 63 of the upper unit UA and lamp Y of the lower unit LA of that signal are deenergized so that, With lamp l3E lighted, the signal displays a single red light to indicate stop. When the neutral relay N is energized and the polarized relay is deenergized (see signal l2) operating Winding 625 of the upper unit UA of that signal is energized in the reverse direction by a circuit which passes from terminal B through front contact 64 of relay l2V, back point of contact 65 of relay EZH, operating winding 53, back point of contact 66 of relay IQH, and iront contact 61 of relay 82V to terminal C so that, when lamp lEE is lighted, signal l2 is in condition to display a single yellow light to indicate approach next signal prepared to stop. When relay H is energized in the reverse ydirection (see signal il) operating Winding 63 of upper unit UA of that signal is energized inthe reverse direction by a circuit which passes from terminal B through reverse polar contact 68-69 of relay IIH, front point of contact I of relay IIH, winding 63, front point of contact 1I of relay I IH, and reverse polar contact 12-13 of relay IIH to terminal C; and the lower unit LA of that signal is energized by a circuit which passes from terminal B through reverse polar contact 'I4-I5 of relay IIH, front contact I6 of relay HH and lamp Y to terminal C. Signal I I, therefore, when lamp I IE is lighted is in condition to display a yellow lampI above a 4yellow lamp to indicate approach next signal at medium speed. When relay H is energized in the normal direction (see signal I0) operating winding 63 of upper unit UA of that signal is energized by a circuit which passes from terminal B through normal polar contact 'I1-'I2 of relay IDH, front point of contact 'I8 of relay IDH, operating winding 63, front point of contact 19 of relay I 0H, and normal polar contact 69-80 of relay IDH to terminal C, so that, when lamp IDE is energized, signal IU is in condition to display a single green light to indicate proceed at normal speed.

Since the relays H and V control the line circuits for the section next in rear in exactly the same manner as described for the relays H and J, shown in Figs. 1A and 1B, it is thought that a detailed explanation is not required for the apparatus shown in Figs. 2A and 2B. It will be considered suiiicient to state that when both relays H and V are deenergized, the line circuit to the rear will be supplied with alternating current energy only, when relay V only is energized, the line circuit to the rear will be supplied in the reverse direction with direct current only, and when the relay H is energized in either direction, its line circuit to the rear will be supplied in the normal direction with direct current only.

Summing up for the system illustrated in Figs. 2A and 2B, it will be seen that when a section is occupied by a train, the signal for that section will display a stop indication comprising a single red light; and the signals for the first, second, and third sections in rear of such occupied section Will display, respectively, an approach indication comprising a single yellow light, an approach medium indication comprising two yellow lights and a proceed indication comprising a single green light provided that another train is occupying the section immediately in rear of such signals so that the associated approach lighting relay ER is deenergized.

It will be readily apparent that the retained neutral feature of the relays H will prevent successive tumble-down of the signal control relays to the rear as previously explained for the relays H shown in Figs. 1A and 1B.

Referring now to Figs. 3A and 3B, the system illustrated herein is similar in many respects to the systems illustrated in the previous figures. The principal difference lies in the fact that alternating current is supplied to the line circuit for the control of the second proceed indication in rear of an occupied section whereas in the systems illustrated in Fig. 1A and 1B and in Figs. 2A and 2B, alternating current is supplied to the line circuit for the control of the first proceed indication in rear of an occupied section.

Each section is provided with a signal having an upper unit U comprising a red, a yellow, and a green lamp and a lower unit L comprising a red and a green lamp.

Each section is provided with a polarized direct current signal control relay HA and with the usual neutral direct current signal control relay V.

Each polarized relay HA is connected directly to the associated line circuit and each neutral relay V is connected to such associated line circuit through a rectifier Q, a transformer M, and a condenser D.

The high impedance of the direct current relays HA will prevent its flow of alternating current in these relays and with the condensers D and transformers M will prevent the iiow of direct current in the relays V.

Each section is provided also with the usual alternator A for supplying alternating current to the line circuit for the section next in rear.

Associated with each section is a pole-changing relay designated by the reference character HP with a prefix the same as the reference character of the associated signal. The relays HP have a slow releasing characteristic and are utilized to control jointly with the associated relays HA and V, the line circuit for the section next in rear.

The relays HA and V control the associated signals in the following manner: When both relays HA and V are deenergized (see signal I3) the red lamp R. of the upper unit U of that signal is lighted by a circuit which passes from terminal B through back point of Contact 8I of relay I 3HA, back point of contact 82 of relay I3V and lamp R to terminal C; and the red lamp R of the lower unit 6 of that signal is lighted by a circuit which passes from terminal B through back point of contact 83 of relay I 3V and lamp.

R to terminal C. Signal I3, therefore, is displaying a red light above a red light to indicate stop. When relay HA is energized in the reverse direction and relay V is deenergized (see signal I2) the yellow lamp Y of the upper unit U of that signal is lighted by a circuit which passes from terminal B through front point of contact 84 of relay IZHA, reverse polar contact 85-86 of relay IZHA and lamp Y to terminal C; and the red lamp R of the lower unit L of that signal is lighted by a circuit which passes from terminal BA through back point of contact 8l of relay I2V and lamp R to terminal C. Signal I2, therefore, is displaying a yellow light above a red light to indicate prepare to stop at next signal. When relay HA is deenergized and relay V is energized (see signal II) the yellow lamp Y of the upper unit U of that signal is lighted by a circuit which passes from terminal B through back point of contact 88 of relay III-IA, front point of contact 89 of relay IIV, and lamp Y to terminal C; and the green lampl G of the lower unit L of that signal is lighted by a circuit which passes from terminal B through front point of contact 90 of relay I IV, and lamp G to terminal C. Signal Il, therefore, is displaying a yellow light above a green light to indicate approach next signal at medium speed. When relay V is deenergized and relay HA is energized in the normal direction (see signal I Il) the green lamp G of the upper unit U of that signal is lighted by a circuit which passes from terminal B through front point of contact SI of relay IUI-IA, normal polar contact 85-92 of relay IUHA, and lamp G to terminal C; and the red lampR of the lower unit U of that signal is lighted by a circuit which passes from terminal B through back point of contact 93 of relay IOV, and lamp R to terminal C'. Signal IU, therefore, is displaying a green light above a red light to indicate proceed at normal speed.

As shown in the drawings, the section immediately to the right of location Z is occupied by the train K so that both relays ISHA and I3V are deenergized. When both relays IBI-IA and I3V are deenergized, the relay IZHA is energized by direct current in the reverse direction over a circuit Which passes from terminal B, at signal I3, through back point of contact 94 of relay I3HA, back contact 95 of relay I3V, Wire 46, secondary winding 33 of transformer I3N, wire 31back point of contact 91 of relay I SHP, front contact 98 of relay GTR, front contact S9 of relay 5TR, relay I2I-IA, front contact |00 of relay ETR, front contact IUI of relay 6TR, and back point of contact |02 of relay ISI-IE to terminal C. When relay IZHA is energized in the reverse direction and relay IZV is deenergized, alternator IZA is energized by direct current over a circuit which passes from terminal B through back contact |03 of relay I2V, front Contact |04 of relay IZHA, reverse polar contact IUE-|06 of relay IZHA, wire 34, and alternator |2A to terminal C; and relay IIHA is energized by alternating current over a circuit IZV, and wire 33 to the other terminal of secondary winding 30 of transformer |2N. When relay IIV is energized and relay IIHA is deenergized, relay III-IP is energized by a circuit which passes from terminal B through front point of contact IIE of relay IIV, back point of contact IIB of relay III-IA and relay IIHP to terminal C; and relay |HA is energized by direct current in the normal direction over a circuit Which passes from terminal B, at signal II,

through front point of contact III of relay III-IP, front contact IIB of relay ZTR, front contact IIO of relay ITR, relay IUHA, front contact |20 of relay ITR, front contact I2I of relay 21R, and front point of contact |22 of relay III-IP to terminal C. When relay IUI-IA is energized in the normal direction and relay |0V is deenergized, relay IOHP is energized over a circuit which passes from terminal B through back point of contact |23, normal polar' contact I 2li-|25 of relay IOHA, front point of contact I 20 of relay IIJHA, and relay IDHP to terminal C; and the line circuit for the section next in rear of section W-X is supplied With direct current energy in the normal direction over front points of contact of relay I BHP so that the signal (not shown) controlled by that line circuit is also displaying its normal proceed indication.

In the signaling systems illustrated in Figs.

r 3A; and 3B, therefore, the two signal control yline circuit to the rear is supplied only with alternating'r current energy. When the neutral relay is energized and the polarized relay is deenergized, the associated signal indicates approach next signalat medium speed and the line circuit to the rear is supplied only with direct current in the normal direction. When the polarized relay is energized in the normal direction and the neutral relay is deenergized, the associated signal indicates proceed at normal speed and the line circuit to the rear is supplied only with direct current energy in the normal direction so that the signal (not shown) controlled by that line circuit is also displaying the normal proceed indication.

It will be noted that the pole changing relays HP have a slow releasing characteristic. This feature prevents momentary opening of the line circuit to the rear so that successive tumbledowny of the signal control relays to the rear is avoided. For example', when the train K passes out of the section to the right of signal I3 so that relay I IHA becomes energized in the normal direction and relay IIV becomes deenergized to causefsignal I I to display the normal indication, energization of relay I IHP is transferred from the circuit which includes front point of contact I I5 of relay I IV and back point of contact I|6 of relay I IHA to a circuit which includes back point of contact H5 of relay IIV, reverse polar contact I29-I25of relay III-IA, and front point of contact IIG of relay IIHA. Relay IIHP, however, does not open the front points of its contacts II'I and |22 during this transfer of control so that energization of the line circuit for section W-X and successive sections to the rear is not disturbed.

Referring now to Fig. 4, which illustrates the alternators A in detail, the reference character |30 designates an elastic member which is caused to vibrate between terminals |3I and |32 by a control Winding |33. In the deenergized condition, member |30 does not connect with either terminal |3| or |32 but does connect with a terminal |34; When energy is supplied to the alternator A, winding |33 will attract member |30 causing it to connect with terminal |32 and to move .away from terminal |34, causing wind. ing |33 to become deenergized. Upon the deenergization of winding |33, the resilience of member |30 will cause it to move away from terminal I 32 and to connect with terminal I3| as well as with terminal |34. The circuit for winding |33 being then again completed through terminal |34, winding |33 vwill again attract member |30 causing the cycle of operation just described to be repeated. Winding |33 will then be repeatedly energized and deenergized as long as energy is supplied to its control circuit.

When member |30 connects with terminal |32, current is supplied to the right-hand portion of the primary winding 35 of the transformer N; and when member |30 connects with terminal |3I, current is supplied in the opposite directio-n to the left-hand portion of primary winding 35. Alternating current, therefore, will be induced in the secondary winding 36 of transformer N.

It will be readily apparent from the foregoing description how the alternators A will supply alternating current to the line circuit foi` the section next in rear when that line circuit is connected to wires 3l and 40 provided, of course, that wire 34 is connected to terminal B and that winding I 33 is connected to terminal C.

Referring now to Figs. 5A and 5B, each section is provided with a signal which comprises an upper unit UA and a lower unit LB both of which are similar in all respects to the searchlight signal mechanisms UA of the signals shown in Figs. 2A and 2B with the exception that the lower units LB are capable of displaying a green light or a red light but not a yellow light.

In addition to the usual source of direct current, the terminals of which are identied by the reference characters B and C, each section is provided also with a source of alternating current the terminals of which are designated by the reference characters BX and CX. This source of alternating current may be any convenient commercial source or may be generated locally at eachsignal by apparatus not shown.

Each upper searchlight mechanism is provided with a lamp UE and each lower searchlight mechanism is provided with a lamp LE.

Associated with each section for controlling the associated lamps UE and LE is an approach lighting relay designated by the reference character ER with a prex the same as the reference character of the associated signal.

Each approach lighting relay ER is connected in series with the line circuit for the section next in rear and is provided with an asymmetric unit l35 connected across its operating winding and poled so as to force the direct current to flow through the operating winding but to permit each half-wave of the alternating current to by-pass the operating winding. Each relay ER, therefore, remains energized as long as the line circuit with which it isk associated remains closed regardless of whether such line circuit is supplied with direct current or with alternating current.

The lamps UE and LE are controlled by a back contact of the associated relay ER sov that these lamps become lighted only when such relay ER is deenergized. For example, the lamps iBUE and ISLE at signal I3 are both governed by back Contact M4 of relay USER. Since relay I 3ER will become deenergized so that its back contact |44 will be closed only when section Y-Z is occupied by a train, lamps iUE and I SLE will be lighted only when section Y-Z is occupied.

Each of the lamps UE and LE for the remaining signals is controlled by the associated relay ER in a manner similar to that just described for signal I3.

Operably connected to each upper unit UA is a Contact E3B-IST which becomes closed only when the signal is in the clear indication position, a contact litt-|38 which becomes closed when the signal is in either the caution or stop indication position, a contact E39-|46 which becomes closed only when the signal is in the caution indication position, and a contact 23e- HH which becomes closed when the signal is in either the clear or stop indication position.

Operably connected to each lower unit LB is a contact |42-l133 which becomes closed only when the signal is in the clear indication position.

Each section is provided with a line circuit including a pair of line wires controlled by the associated track relays and extending to the signal for the section next in advance.

Each lower mechanism LB is connected to the associated line circuit through a rectifier, a transformer and a condenser designated by the reference characters Q, M, and D, respectively, each with a prex the same as the reference characters of the associated signal. That is, each mechanism LB responds only when its line circuit is supplied with alternating current.

Associated with each section is a repeating relay designated by the reference character LP with a prex the same as the reference character of the associated signal. Each relay LP is controlled by the lower mechanism LB of the associated signal and receives its energy over the associated line circuit. That is, each LP relay is energized only when the associated lower mechanism is also energized. For example, the relay IGLP is controlled over clear contact It-IQS of lower mechanism LB of signal I0 so that when the mechanism is energized the relay iLP also receives energy from the line circuit which supplies energy to the lower mechanism LB.

Each upper mechanism UA is connected to the associated line circuit through either iront or back contacts of the associated relay LP. When the relay LP is deenergized, that is, when the associated line circuit is not being supplied with alternating current energy, the upper mechanism is connected directly to the line circuit, whereas when relay LP is energized, that is, when the associated line circuit is supplied with alternating current energy, the upper mechanism is connected to the line circuit through rectiiier Q, transformer E, and condenser D.

In other words, the upper mechanism UA of each signal is responsive to direct current only but both mechanisms UA and LB are responsive to alternating current. As will be explained more in detail hereinafter, the relays LP are effective also for connecting other relays to the associated line circuit when the relays LP are energized.

Associated with each section is a pole changing relay designated by the reference character PC with a prex the same as the reference character of the associated signal. Each relay PC is governed by the upper signal mechanism UA of the associated signal in such a manner that each relay PC is energized only when the upper mechanism UA of the associated signal is in either its clear or caution indication position. For example, relay IDPC may be energized by a circuit which includes clear contact I3E-I3'I as well as clear and stop contact I39-I4I of the upper mechanism UA of signal I 0, or may be energized by another circuit which includes caution contact I39-I40 as well as caution and stop contact ISS-|38 of such upper mechanism UA. Each relay PC is effective for governing the polarity of the direct current energy supplied to the line circuit for the section next in rear.

Associated with each section is another repeating relay designated by the reference character UP with a prex the same as the reference character of the associated signal. Each relay UP is governed by the upper signal mechanism UA of the associated signals. For example, the relay IUUP is governed by clear contact IBS-|37 of upper mechanism UA of signal Ill so that relay IUUP is energized only when such mechanism is in its clear indication position.

Also associated with each section is an alternating current power transfer relay designated by the reference character PO with a prefix the same as the reference character of the associated signal. Each relay PO is governed by the associated source of alternating current and by the associated relay UP. For example, the relay llPO is governed by front contact |45 of relay IIlUP so that relay IUPO will be energized only when relay IBUP is energized provided that the alternating current is present at signal I0.

Each relay PO is effective to connect the line circuit for the section next in rear with the associated source of alternating current or with the associated source of direct current depending upon whether such relay PO is energized or deenergized, respectively.

The operation of the signaling system illustrated in Figs. 5A and 5B will probably be best understood by tracing the circuits and explaining the operation simultaneously. As shown in the drawings, a train K occupies the section immediately to the right of signal I 3 so that both upper and lower mechanisms of that signal are deenergized. Signal I3, therefore, when lamps I3UE and I3LE are lighted will display a red light above a red light to indicate stop. When signal I 3 is in this condition, relay I3PC is deenergized and relay I 3UP is also deenergized so that relay I3PO likewise is deenergized.

Since both relays ISPC and I3PO are deenergized, operating winding 63 of upper mechanism UA of signal I2 is supplied with direct current energy in the reverse direction over a circuit Which passes vfrom terminal B, at signal I3, through back point of contact of relay I3PO, approach lighting relay I3ER, back point of contact I 41 of relay I3PC, front contact |48 of relay GTR, front contact M9 of relay 5TR, back point of contact |58 of relay I 2LP, operating Winding 53 of signal I2, back point of contact |5| of relay I'sLP, front contact |52 of relay 5TR, front contact |53 of relay GTR, back point of contact |513 of relay ISPC, and back point of contact |55 of relay I3PO to terminal C. Signal I2, therefore, when lamps |2UE and I 2LE are lighted, will display a yellow light above a red light to indicate prepare to stop at next signal. When signal I2 is in this condition, relay |2PC is energized by a circuit which passes from terminal B through back point of contact |56 of relay IZLP, caution and stop contact I 36-I38 as Well as caution contact ISS-I4!) of signal I2, relay IZPC, and back point of contact |51 of relay IZLP.

When relay |2PC is energized and relay I2PO is deenergized, operating winding 63 of upper mechanism UA of signal I I is supplied with direct current in the normal direction over a circuit which passes from terminal B through back point of contacts |58 of relay |2PC, relay I2ER, front point of contact |59 of relay |2PC, front contact |66 of relay TR, front contact I 6| of relay ETR, back point of Contact |52 of relay IILP, operating winding 53 of signal II, back point of contact |83 of relay IILP, front contact |84 of relay STR, front contact |65 of relay dTR, front point of contact |66 of relay |2PC, and'back point of contact |61 of relay |2PO to terminal C. Signal II, therefore, when lamps II UE and IILE are lighted, will display a green light above a red light to indicate approach next signal at medium speed. When signal II is in this condition, relay IIUP is energized by a circuit which passes from terminal B through back point of contact |58 of relay IILP, clear contact ISE-|31 of signal II, relay IIUP, and back point of contact |69 of relay IILPy to terminal C; relay IIPO is energized over front contact |18 of relay IIUP; and relay IIPC is energized over a circuit Which passes from terminal B over the same path as just traced for relay IIUP up to and including clear contact I 36-I31 of signal II, and thence through clear and stop contact ISS-MI of signal II, relay IIPC and back point of Contact |69 of relay IILP.

Since both relays I IPC and I IPO are energized,

, the primary Win-ding |1I of transformer IDM will be supplied with alternatingl current energy/over. a circuit which passes from terminal BX, atv signal I2, through front point of contact` |12 of relay IIPO, relay IIER, front point of contact |13 of relay IIPC, front contact I14'of relay ZTR, front contact |15 of relay ITR, condenser IUD, primary winding |1| of transformer IIJM, front contact |16 of relay ITR, front contact |11 of relay 2TR, front point of contact I18'of` relay IIPC and front point of contact |19 of; relay IIPO to terminal CX.

When primary Winding |1| of transformer IiD is energized, current is induced in the secondary Winding |84 of this transformer'so that alternating current is supplied to the alternating: current input terminals of the rectifier IUQ. Consequently, operating winding 63 of the lower mechanism LB of the signal I0, which mechaf nism is connected to the direct current output terminalr of the rectier I UQ, is supplied with; direct current of normal polarity so that thismechanism is caused to assume itsclear indication position.

When the lower mechanism LB of signal I IJ is in its clear indication p0ston, relay IULP is energized by a circuit which passes fromv one direct current output terminal of rectifier IUQ through clear contact |42-I43 of signal I0; and relay LP to the other direct current output terminal of rectier I UQ.

When relay IIJLP is energized, theoperating winding 630i the upper mechanism UAof signal. I0 is energized in the normal direction over a` circuit which passes from one direct current output terminal of rectifier IUQ throughfront point of contact |88 of relay IULP, o-perating'winding 63, and front point of contact I8I of relay IIlLP to the other output terminal of rectifier IIIQ.

Signal Ill, therefore, when lamps IGUErand I IILE are lighted, is in condition to display a .green light above a green light to indicate pro-- ceed at normal speed,

When signal I0 4is in this condition, relay IDUP is energized by a circuit which passes from oneoutput terminal of rectier IIJQ throughfrontA point of contact |82 of relay IDLP, cleai` contactv I36-I31of signal III, relay IIIUP, and front point of contact |83 of relay IULP to; the oth-eroutput terminal of rectier IUQ'; relay IUPC is. energized by a circuit which passes from one output terminal of rectier IIlQ4 through front. point of contact |82 of relay IIJLP, clear'ccn'- tact ISS-|31 as. well as clear and stop contact I39|4I of signal Ill, relay IUPC, and'front point of contact |83 of relay II'ILP to thefother output terminal of rectifier IIJQ; andrelay IIJPO is energized by a circuit which passes from terminal BX through front contact |45 of relay IIJUP, and relay IIlPO` to terminal CX.

Since both relays IDPC and IUPO are energized, it is readily apparent that the line` circuit for the section next in rear is supplied with alternating current energy so that the signal (not shown) controlled by that line circuit is also in its normal proceed condition.

It will be noted that both the relays PC and UP have a slow release characteristic. The feature of relays UP prevents the momentary release of the associated relaysr PO when the control of the relays UP is being transferred' from the back to the front points of the contacts of the associated relays LP, and this feature of the relays PC prevents the momentary release of the relays` PC when the control-forr these relays isbeingtransferredfrom tlfielcack#V to the front points of the contacts of the associated relays LP as well as when the control for these relays is being transferred from the caution contacts to the clear contacts of the associated signal. Since the relays PC and PO do not become released during such periods, the energization of the line circuit for the section next in rear is not disturbed and, consequently, successive tumble-down of the signal control circuits to the rear is avoided. For example, when the train K moves out of the section to the right of location Z so that the line circuit for signal II is supplied with alternating current energy to cause signal II to assume the normal proceed condition, the control circuit for relay I IUP will be opened momentarily during the time the control is being transferred from the back points of contacts IBB and IBS of relay IILP toI the front points of thes-e contacts. The slow release characteristics of relay IIUP, however, will maintain its front contact I l closed during this period so that relay IIPO will not become released. Or, for example, when the train K vacates the section to the right of location Z so that signal I2 is caused to assume the condition proper for displaying a green light above a red light instead of a yellow light above a red light, the control circuit for relay I2PC will be opened momentarily during the time the control for this relay is being transferred from the caution contact ISS-MI) to the clear contact I36-I3'I of signal I2. Relay IZPC, however, due to its slow release characteristic will maintain its contacts in the energized condition during this period.

As hereinbefore pointed out, each section is provided with a source of direct current and with a Source of alternating current. When a section is occupied by a train, the energy required by the lamps for the associated signal as well as the energy required for the line circuit for the section next in rear will be supplied by the source of direct current at such signal. For example, the line circuit for section Y-Z is supplied with energy from the source of direct current at signal I3 and the lamps I3UE and I3LE would be also supplied with energy from this source of direct current if relay ISER should become deenergized by another train occupying section Y-Z. The circuit for lamps ISUE and I3LE may be traced from terminal B through back point of contact |46 of relay I SPO, back contact IM of relay I 3ER, lamps I3UE and ISLE in multiple, and back point of contact |55 of relay I3PO to terminal C.

At signal I2, the energy required by relay IZPC and the energy required by the line circuit f .or section X-Y as well as the energy which may be required to light the lamps IZUE and IQLE is all supplied by the source of direct current at that signal.

At signal II, the energy required by relays IIPC and IIUP is supplied by the source of direct current at that signal but the energy required by the line circuit for the section W-X and the energy required by relay I IPO as well as the energy which may be required for the lamps IIUE an-d IILE is supplied by the source or" alternating current at that signal.

At signal IU, the energy required for the relays IULP, IOPC, IGPO, and IUUP and the energy required for the line circuit for the section next in rear as well as the energy which may be required by the lamps IUUE and IDLE is supplied entirely by the source of alternating current at that signal.

In the event of failure of the source of alternating current, my system will function as a two indication signaling system. For example, if the alternating current at signal II should become absent, the relay IIPO would become deenergized so that the back points of its contacts |12 and IIS would become closed to supply direct current energy in the normal direction to the line circuit for the control of signal IIJ with the result that signal I0 would assume the condition proper for displaying a green light above a red light instead of the normal proceed indication.

To sum up regarding the two sources of current, each signal is provided with an alternating current source of energy which supplies the entire load required by my system as long as the signals display their normal proceed indimore restrictive indications and which source of direct current energy serves also as a reserve source of current in event of failure of the source of alternating current.

It will be apparent that since the stretch of railway track ordinarily will be unoccupied for the greater portion of the time, the consumption of direct current energy will be relatively small. This feature provides for a material reduction in the cost of maintenance particularly when the direct current energy is supplied by primary batteries.

From the foregoing description, it is apparent that each of the modiiications embodying my invention provides a distinctive control for each of three sections in the rear of an occupied section whereby a three block, four indication system of signaling is produced which systems each require but two line control wires extending from signal to signal.

Although I have herein shown and described only four forms of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. I n combination, a plurality of successive sections of railway track each having a track circuit including a track relay, a line circuit for each section governed by the associated track relay, a polarized direct current relay and an alternating current relay for each section connected to the associated line circuit, a source of direct current for each section, an alternator for each section for converting direct current to alternating current, means including back contacts of both said direct current and said alternating current relay for connecting the associated alternator to the associated direct current source and to the line circuit next in rear of the associated section, means including front contacts of the alternating current relay and back contacts of the direct current relay for supplying such rear line circuit with direct current only of reverse polarity, means including front contacts of said direct current relay for supplying such rear line circuit with direct current only of normal polarity and a signal for each section governed by said two associated relays.

2. A railway signal system comprising a irst and a second as well as a third track section over which traiiic normally progresses in the order named, a track circuit including a track relay for each section, a line circuit for each section governed by the associated track relay and including a pair of line wires, a polarized direct current line relay for each section connected to the associated line circuit, an auxiliary line relay for each section also receiving energy from the associated line circuit and responsive only when said line circuit is supplied with alternating current, means including back contacts of both line relays for the third section for supplying alternating current to the line circuit for the second section when the third section is occupied, means including front contacts of the auxiliary relay for the second section and back contacts of the polarized relay for that section for supplying the line circuit for the first section with direct current of reverse polarity, a signal for said first section, and means including reverse polar contacts of the polarized relay for the rst section for causing said signal to indicate that the third section is occupied.

3. In combination, a stretch of railway track divided into a plurality of successive block sections each having a pair of conductors governed by traiiic conditions in said section, each of said block sections having a signal capable of displaying a normal proceed indication and a plurality of restrictive proceed indications, each of said signals having associated therewith iirst and second control devices energized from the conductors for the section with which the signal is associated, the first control device being responsive to alternating current supplied to said conductors, the second control device being responsive to direct current supplied to said conductors, each signal having associated therewith an alternating current supply mechanism operative on the supply of direct current thereto to supply alternating current to a circuit from which alternating current may be supplied to the conductors of the adjacent block section to the rear, each signal also having associated therewith a source of direct current, said first control device being operative when energized to condition the signal with which it is associated to display a restrictive proceed indication, the second control device being operative when energized while the first control device is deenergized to Condition said signal to display its normal proceed indication, the second device controlling the supply of direct current to the associated alternating current supply mechanism.

4. In combination, a stretch of railway track divided into a plurality of successive block sections each having a pair of conductors governed by traiiic conditions in said section, each of said block sections having a signal Capable of displaying a normal proceed indication and a plurality of restrictive proceed indications, each of said signals having associated therewith rst and second control devices energized from the conductors for the section with which the signal is associated, the rst control device being responsive to alternating current supplied to said conductors, the second control device being responsive to direct current supplied to said conductors, each signal having associated therewith an alternating current supply mechanism operative on the supply of direct current thereto to supply alternating current to a circuit from which alternating current may be supplied to the conductors of the adjacent block section to the rear, each signal also having associated therewith a source of direct current, said iirst control device being operative when energized to condition the signal with which it is associated to display a restrictive proceed indication, the second control device being operative when energized while the rst control device is deenergized to condition said signal to display its normal proceed indication, the first and second control devices jointly controlling the supply of direct current to the associated alternating current supply mechanism, one of said control devices controlling the connection of the source of direct current to the conductors of the adjacent block section to the rear.

5. In combination, a stretch of railway track divided into a plurality of successive block sections each having a pair of conductors governed by traiic conditions in said section, each of said block sections having a signal capable of displaying a normal proceed indication and a plurality of restrictive proceed indications, each of said signals having associated therewith first and second control devices energized from the conductors for the section with which the signal is associated, the rst control device being responsive to alternating current supplied to said conductors, the second control device being responsive to direct current supplied to said conductors, each signal having associated therewith an alternating current supply mechanism operative on the supply of direct current thereto to supply alternating current to a circuit from which alternating current may be supplied to the conductors of the adjacent block section to the rear, each signal also having associated therewith a source of direct current, said first control device being operative when energized to condition the signal with which it is associated to display a restrictive proceed indication, the second control device being Operative when energized while the rst control device is deenergized to condition said signal to -display its normal proceed indication, said first and second control devices jointly controlling the supply of direct current to the associated alternating current supply mechanism, said first control device also controlling the connection of the source of direct current to the conductors of the adjacent block section to the rear.

6. In combination, a stretch of railway track divided into a plurality of successive block sections each having a pair of conductors governed by traic conditions in said section, each of said block sections having a signal capable of displaying a normal proceed indication and a plurality of restrictive proceed indications, each of said signals having associated therewith first and second control devices energized from the conductors for the section with which the signal is associated, the first control device being responsive to alternating current supplied to said conductors, the second control device being responsive to direct current supplied to said conductors, each signal having associated therewith an alternating current supply mechanism operative on the supply of direct current thereto to supply alternating currentvto a circuit from which alternating current may be supplied to the conductors trol device is deenergized to condition said signal to display its normal proceed indication, said rst and second control devices jointly controlling the supply of direct current to the associated alternating current supply mechanism and the connection of the source of direct current to the conductors of the adjacent block section to the rear.

'7. In combination, a stretch of railway track divided into a plurality of successive block sections each having a pair of conductors governed by traffic conditions in said section, each of said block sections having a signal capable of displaying a normal proceed indication and a plurality of restrictive proceed indications, each of said signals having associated therewith first and second control devices energized from the conductors for the section with which the signal is associated, the first control device being responsive to alternating current supplied to said conductors, the second control device being responsive to direct current supplied to said conductors, each signal having associated therewith an alternating current supply mechanism operative on the supply of direct current thereto to supply alternating current to a circuit from which alternating current may be supplied to the conductors of the adjacent block section to the rear, each signal also having associated therewith a source of direct current, said iirst control device being operative when energized to condition the signal with which it is associated to display a restrictive proceed indication, the second control device being operative when energized while the rst control device is deenergized to condition said signal to display its normal proceed indication, said second control device controlling the supply of direct current to the associated alternating current supply mechanism, said iirst and second control devices jointly controlling the connection of the source of direct current to the conductors of the adjacent block section to the rear.

8. In combination, a stretch of railway track divided into a plurality of block sections each having a pair of conductors governed by traffic conditions in said section, each of said block sections having a signal capable of displaying a normal proceed indication and a plurality of restrictive proceed indications, each of said signals having associated therewith a first and a second control device energized from the conductors for the block section with which the said signal is associated, the first control device being responsive to alternating current supplied to said conductors, the second control device being responsive to direct current supplied to said conductors, said second control device being selectively responsive to the polarity of direct current supplied thereto, each of said signals having associated therewith an alternating current supply mechanism operative on the supply of direct current thereto to supply alternating current toa circuit from which alternating current may be supplied to the conductors of the adjacent block section in the rear, each of said signals also having associated therewith a source of direct current, the first control device being operative when energized to condition the signal to display a restrictive proceed indication, the second control device being operative when energized with direct current of a particular polarity at a time when the iirst control device is deenergized to condition the signal to display the normal proceed indication, the second control device controlling ythe supply of direct current to the associated alternating current supply mechanism, said rst control device controlling the connection of the source of direct current to the conductors of the adjacent block section to the rear.

9. In combination, a stretch of railway track divided into a plurality of block sections each having a pair of conductors governed by traffic conditions in said section, each of said block sections having a signal capable of displaying a normal proceed indication and a plurality of restrictive proceed indications, each of said signals having associated therewith a rst and a second control device energized from the conductors for the block section with which the saidv signal is associated, the first control device being responsive to alternating current supplied to said conductors, the second control device being responsive to direct current supplied to said conductors, said second control device being selectively responsive to the polarity of direct current supplied thereto, each of said signals having associated therewith an alternating current supply mechanism operative on the supply of direct current thereto to supply alternating current to a circuit from which alternating current may be supplied to the conductors of the adjacent block section in the rear, each of said signals also having associated therewith a source of direct current, the rst control device being operative when energized to condition the signal to display a restrictive proceed indication, the second control device being operative when energized with direct current of a particular polarity at a time when the iirst control device is deenergized to condition the signal to display the normal proceed indication, said rst and second control devices jointly controlling the supply of direct current to the associated alternating current supply mechanism, said first control device controlling the connection of the source of direct current to the conductors of the adjacent block section to the rear.

10. In combination, a stretch of railway track divided into a plurality of block sections each having a pair of conductors governed by traiiic conditions in said section, each of said block sections having a signal capable of displaying a normal proceed indication and a plurality of restrictive proceed indications, each of said signals having associated therewith a i'lrst and a second control device energized from the conductors for the block section with which the said signal is associated, the first control device being responsive to alternating current supplied to said conductors, the second control device being responsive to direct current supplied to said conductors, said second control device being selectively responsive to the polarity of direct current supplied thereto, each of said signals having associated therewith an alternating current supply mechanism operative on the supply of direct current thereto to supply alternating current to a circuit from which alternating current may be supplied to the conductors of the adjacent block section in the rear, each of said signals also having associated therewith a source of direct current, the first control device being operative when energized to condition the signal to display a restrictive proceed indication, the second control device being operative when energized with direct current of a particular polarity at a time when the first control device ls deenergized to condition the signal to display the normal proceed indication, said rst and second control devices jointly controlling the supply of direct current to the associated alternating current supply mechanism, said second control device controlling the connection of the source of direct current to the conductors of the adjacent block section to the rear.

ll. In combination, a stretch of railway track divided into a plurality of block sections each having a pair of conductors governed by trafhc conditions in said section, each of said block sections having a signal capable of displaying a normal proceed indication and a plurality of restrictive proceed indications, each of said signals having associated therewith a first and a second control device energized from the conductors for the block section with which the said signal is associated, the iirst control device being responsive to alternating current supplied to said conductors, the second control device being responsive to direct current supplied to said conductors, said second control device being selectively responsive to the polarity of direct current supplied thereto, each of said signals having associated therewith an alternating current supply mechanism operative on the supply of direct current thereto to supply alternating current to a circuit from which alternating current may be supplied to the conductors of the adjacent block section in the rear, each of said signals also having associated therewith a source of direct current, the iirst control device being operative when energized to condition the signal to display a restrictive proceed indication, the second control device being operative when energized with direct current of a particular polarity at a time when the iirst control device is deenergized to condition the signal to display the normal proceed indication, said rst and second control devices jointly controlling the supply oi direct current to the associated. alternating current supply mechanism, and also jointly controlling the connection of the source of direct current to the conductors of the adjacent block section to the rear.

l2. In combination, a stretch of railway track divided into a plurality of block sections each having a pair of conductors governed by traic conditions in said section, each of said block sections having a signal capable of displaying a normal proceed indication and a plurality of restrictive proceed indications, each of said signals having associated therewith a iirst and a second control device energized from the conductors for the block section with which the said signal is associated, the iirst control device being responsive to alternating current supplied to said conductors, the second control device being responsive to direct current supplied to said conductors, said second control device being selectively responsive to the polarity of direct current supplied thereto, each of said signals having associated therewith an alternating current supply mechanism operative on the supply of direct current thereto to supply alternating current to a circuit from which alternating current may be supplied to the conductors of the adjacent block section in the rear, each of said signals also having associated therewith a source of direct current, the iirst control device being operative when energized to condition the signal to display a restrictive proceed indication, the second control device being operative when energized with direct current of a particular polarity at a time when the first control device is deenergized to condition the signal to display the normal proceed indication, said second control device controlling the supply of direct current to the associated alternating current supply mechanism, said rst and second control devices jointly controlling the connection of the source of direct current to the' conductors of the adjacent block section to the rear.

13. In combination, a stretch of railway track divided into a plurality of block sections each having a pair of conductors governed by trafc conditions in said section, each of said block sections having a signal capable of displaying a normal proceed indication and a plurality of restrictive proceed indications, each of said signals having associated therewith a iirst and a second control device energized from the conductors for the block section with which the said signal is associated, the iirst control device being responsive to alternating current supplied to said conductors, the second control device being responsive to direct current supplied to said conductors, said second control device being selectively responsive to the polarity of direct current supplied thereto, each of said signals having associated therewith an alternating current supply mechanism operative on the supply of direct current thereto to supply alternating current to a circuit from which alternating current may be supplied to the conductors of the adjacent block section in the rear, each of said signals also having associated therewith a source of direct current, the iirst control device being operative when energized to condition the signal to display a restrictive proceed indication, the second control device being operative when energized with direct current of a particular polarity at a time when the iirst control device is deenergized to condition the signal to display the normal proceed indication, said second control device controlling the supply of direct current to the associated alternating current supply mechanism, said second control device being operative when energized with direct current of said particular polarity to interrupt the supply of direct current to said mechanism.

14. In combination, a stretch of railway track divided into a plurality of block sections each having a pair of conductors governed by traiiic conditions in said section, each of said block sections having a signal capable of displaying a normal proceed indication and a plurality of restrictive proceed indications, each of said signals having associated therewith a first and a second control device energized from the conductors for the block section with which the said signal is associated, the iirst control device being responsive to alternating current supplied to said conductors, the second control device being responsive to direct current supplied to said conductors, said second control device being selectively responsive to the polarity of direct current supplied thereto, each of said signals having associated therewith an alternating current supply mechanism operative on the supply of direct current thereto to supply alternating current to a circuit from which alternating current may be supplied to the conductors of the adjacent block section in the rear, each of said signals also having associated therewith a source of direct current, the first control device being operative when energized to condition the signal to display a restrictive proceed indication, the second control device being operative when energized with direct current of a particular polarity at a time when the iirst control device is deenergized to condition the signal to display the normal proceed indication, said second control device controlling the supply of direct current to the associated alternating current supply mechanism, said second control device being operative when energized with direct current of said particular polarity to interrupt the supply of direct current to vsaid mechanism, said i'lrst control device controlling the connection of the source of direct current to the conductors of the adjacent block section to the rear.

15. In combination, a stretch of railway track divided into a plurality of block sections each hav ing a pair of conductors governed by trai-lic conditions in said section, each of said block sections having a signal capable of displaying a normal proceed indication and a plurality of restrictive proceed indications, each of said signals having associated therewith a rst and a second control device energized from the conductors for the block section with which the said signal is associated, the rst control device being responsive to alternating current supplied to said conductors, the second control device being responsive to direct current supplied to said conductors, said second control device being selectively responsive to the polarity of direct current supplied thereto, each of said signals having associated therewith an alternating current supply mechanism operative on the supply of direct current thereto to supply alternating current to a p circuit from which alternating current may be supplied to the conductors of the adjacent block section in the rear, each of said signals also having associated therewith a source of direct current, the. first control device being operative when energized to condition the signal to display a restrictive proceed indication, the second control device being operative when energized with direct current of a particular polarity at a time when the rst control device is deenergized to condition the signal to display the normal proceed indication, said second control device controlling the supply of direct current to the associated alternating current supply mechanism, said second control device being operative when energized with direct current of said particular polarity to interrupt the supply of direct current to said mechanism, said first and second control devices jointly controlling the connection of the source of direct current to the conductors of the adjacent block section to the rear.

GEORGE R. PFLASTERER. 

